The article presents results of the calculation of pollutants emitted into the atmospheric air in Chita. The approach to the zoning of the city territory with a population of more than 350 thousand people is described. By the results of calculation and assessment of health risks, which are based on the data of modeling the dispersion of harmful impurities, the zones of exposure to chemical impurities were identified. The zoning by the risk degree is relevant for assessing the danger to the population and the impact on the environment. The list of priority impurities was substantiated, taking into account carcinogenic and/or non-carcinogenic risks, and the results of calculations of dispersion and allocation of marker indicators for emissions from enterprises that make the greatest contributions to the air pollution. The methods used in Chita help identify areas with the greatest risks to public health.